1. Field of the Invention
The invention relates to side-opening looseleaf binders.
2. Description of the Prior Art
Known looseleaf mechanisms are characterized by the use of a plurality of rings mounted within a book cover. The individual rings open to receive sheets of paper containing holes matching the particular ring locations. Once loaded, the rings are closed and the paper sheets are captured within the book although they are free to move on the rings in the open or closed book condition.
In known looseleaf mechanisms, paired half rings are employed which open or close simultaneously at their top portions with the book open and lying flat on its back.
Typically two to seven rings per long side of a standard sheet of paper may be employed or in multi-ring designs, as many as twenty-two rings may be employed. A large number of rings assists in distributing page turning wear on individual sheets.
In the known half ring mechanisms, opening of the rings is accomplished by tugging outwardly on the individual half rings. This practice inevitably results in paired rings eventually failing to match at the point of joining. This inhibits easy page turning and escalates page wear. To partially eliminate this problem, levers have been provided in known mechanisms which activate an internal spring toggle and cause all rings to snap open simultaneously. Closing is then accomplished by pressing the opened rings towards one another.
The above described known type of mechanism is sensitive to catastrophic failure if a loaded, closed binder is dropped on a hard surface. This causes the rings to partially open momentarily upon impact.
In order to avoid the above problems, it has been known to employ side opening looseleaf mechanisms. In one known type, three individual acting locking rings per long side of a standard sheet of paper are employed. Each of these locking rings, however, must be individually opened and closed since each locking ring has a slight ball on the end which fits into a slightly smaller aperture. This mechanism is inexpensive since it can possibly be molded in one piece in polyethylene. However, it is time consuming to open and close the individual rings. Other types of side-opening looseleaf mechanisms are known which utilize a set of rings which open or close simultaneously. However, in such structures, large numbers of parts are needed as is well known in the art.